An agricultural seeding machine, such as a row crop planter or grain drill, places the seed at a desired depth within a plurality of parallel seed trenches formed in soil. In the case of a row crop planter, a plurality of row crop units are typically ground driven using wheels, shafts, sprockets, transfer cases, chains and the like. Each row crop unit has a frame, which is movably coupled with a tool bar. The frame may carry a main seed hopper, herbicide hopper and insecticide hopper. If the granular herbicide and insecticide are used, the metering mechanisms associated therewith for the dispensing of the granular product into the seed trench are relatively simple. On the other hand, mechanisms necessary to properly meter seeds at a predetermined rate and to place the seeds at a predetermined relative locations and depth within the seed trench are relatively complicated.
The mechanisms associated with metering and placing of the seeds generally can be divided into a seed metering system and a seed placement system, which are in communication with each other. The seed metering system receives the seeds in a bulk manner from a seed hopper carried by the frame. Different types of seed metering systems can be used such as seed plates, finger plates and seed disk. In the case of a seed disk metering system, a seed disk is formed with a plurality of seed cells spaced about the periphery thereof. Seeds are moved into the seed cells with one or more seeds in each seed cell depending upon the size and configuration of the seed cell. A vacuum or positive pressure airflow may be used in conjunction with the seed disk to assist in movement and retention of the seeds in the seed cells. The seeds are singulated and discharged at a predetermined rate to the seed placement system.
The seed placement system may be categorized as a gravity drop system or a power drop system. In the case of a gravity drop system, a seed tube has an inlet end, which is positioned below the seed metering system. The singulated seeds from the seed metering system merely drop into the seed tube and fall by way of gravitational force from a discharge end thereof into the seed trench. The seed tube may be curved in a rearward manner to assist in directing the seed into the seed trench
A seed placement system of the power drop variety generally can be classified as a seed conveyor belt drop, rotary valve drop, chain drop or air drop. These types of seed placement systems provide somewhat consistent placement of the seeds along a predetermined path at a desired spacing.
Certain seed types, such as flat corn seed with insecticide or other treatments thereon are difficult for vacuum meters to singulate. Poor singulation of difficult seed types is characterized by doubles, skips and bunches of seed carried by the disk. Doubles and skips refer to multiple seeds and no seed, respectively, in each seed cell. Bunches are multiple seeds carried by the seed pool accelerators, which protrude from the surface of the seed disk. These seed types generally are best planted with a flat seed disk in combination with a doubles eliminator.
What is needed in the art is an agricultural seeding machine having an accurate positive seed spacing monitor and an efficient adjustment of a seed metering system.